The French Mission to Lake Chad

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Hydrological model of Lake Chad

A simple and robust water balance model is developed for Lake Chad that simulates water levels and inundated areas according to the inflow (river discharge, precipitation) and outflow to the lake (evaporation, infiltration). In the model, Lake Chad is represented by three reservoirs (the southern basin connected to the north basin and the archipelago), whose water levels can be different during periods of low inputs (current situation) or similar during periods of surplus (pre-1973 situation). In accordance with field observations, the north basin is represented by a soil reservoir that must be filled before water can appear on the surface. The model uses seven optimized parameters: infiltration rate; depth of the soil reservoir; four exchange parameters between reservoirs; and the bottom level of the archipelago. It is calibrated on the period 1970–1996 and validated on the period 1956–2008, using data measured in situ or by satellite (river discharge, precipitation, evaporation, water levels and inundated areas)